Isoeugenol is an important contact allergen: can it be safely replaced with isoeugenyl acetate?

The prevalence of contact allergy to the fragrance mix in individuals with eczema is up to 10%. Within the mix, isoeugenol (CAS 97-54-1) is an important individual allergen. Until May 1998, the IFRA (International Fragrance Association) guidelines suggested that isoeugenol could safely be used at a level of 0.2% in consumer products. In May 1998, IFRA recommended that isoeugenol should not be used at a level that exceeds 0.02% in consumer products, but did not provide guidance on allergen substitution. An alternative to isoeugenol, based on aroma and absence of guidelines on use, is isoeugenyl acetate (CAS 93-29-8). 155 consecutive subjects were patch tested to isoeugenyl acetate (1.2%, 0.4%, 0.13% eth.) and isoeugenol 1% pet. 6 (3.9%) had an allergic reaction to 1.2% isoeugenyl acetate at D4. The reactions to the other 2 dilutions tended to be graded. 8 individuals had at least a palpable erythema by D4 to isoeugenol 1% pet. The majority of individuals allergic to isoeugenol were also intolerant of isoeugenyl acetate. Effective labelling of fragrance substances on consumer products will facilitate monitoring of exposure.